Thermometer bulb



June 2, 1931.

M. E. CHENEY THERMOMETER BULB Filed March 24, 1928 Patented June 2, 1931 UNITED STATES PAT EN OFFICE MosEsE. CHENEY, or LA cnossn, WISCONSIN, ASSIGNOB, BY MEs E AssIG MEN'rs, To MOTO METER GAUGE & EQUIPMENT oon-Pon-ArIoN, or; L NG ISLAND CITY, NEW

YORK, A. CORPORATION OF DELAXVARE THERMOMETER BULB Application filed March 24, 1928. Serial No. $4,499.

This invention relates to an improvement in the manufacture of thermometers and more particularly to an improved method of attaching'one end of a capillary tube to a thermometer bulb of the metallic type Under certain conditions a thermometer bulb of this type is subjected to severe me chanical strains'and high pressures, for example, in the water jacket of agasoline en gine where there is considerable vibration,

'excessive heat, and high pressures at different times, and in the handlingbf same.

In prior constructions considerable difficulty was experienced in sealing the metallic bulb and capillary tube together in such a manner as to withstand the shocks and strains to which it is often subjected."

Solder has often been used for securing the parts together'but it requires some expert obtain an absolutely tight connection.

Attempts have been made to remedy this difficulty by first soldering to the open end of the bulb a separate piece of metal in order to produce a proper bearing surface for the capillary tube "but a much larger area was thereby required to be soldered, the chances of producing a fluid tight joint being greatly reduced and the expense some what increased.

"The capillary tube in this type of thermometer has heretofore never been properly protected againstlaccidental"bends and sharp turns. 'Unless greatcare was used in bending the tube into the desired curve,a severe fracture resulted, that is the tubing was very apt to become kinked rendering the instrument useless.

One part of my invention is a method of making a metallic bulb from a single sheet of metal and by a series of drawing, punchtube having both ends closed except a-small opening in one end insertion of a capillary tube.

Another object of my invention is to provide a metallic thermometer bulb with reduced portion intermediate its ends leaving an open ended part adjacent said reduced portion forming a cup shaped receptacle for mg and spinning operationswork it into a just large enough for the the insertion of flexible protecting means for the capillary tube, preferably an armored tube. v

Another object is to provide a one piece thermometer bulb with a'cup shaped por{ tion for the reception of oneend 'of the protecting means,'a reduced neck portion for supporting a capillary tube, and an enlarged bulb portion. having both .endsclosed except for theflop'ening in said reduced portion.

: Other'objects and advantages will be in part indicated in 1 the following description and in part rendered apparent'therefrom in connection with the annexed drawings.

To enable others skilled in the art so fully to apprehend the underlying features hereof that they may embodythe same in the various ways contemplated by this invention, drawings depicting a preferred typical construction have been annexed as "a part of this disclosure and, in such drawings, like characters of reference denote corresponding parts throughout all the views, of which Figure 1 is an assemblyview ofthe the r mometer bulbshowing the capillary tube and protectingmeans in place. Fig. 2 shows the bulb at an early stage in formation. Fig. 3 is a view of the bulb in one of its intermediate stageso-f completion? Fig. 4 shows the bulb in one stage of analternative method of forming the reduced neck portion.

'Referringflto F l the bulb 10 is preferably made ofcopper or other conveniently worked metal and by a series'of operations such'as punching, drawing and spinning the original piece of metal is formed into the shape shown. Fig. 2 shows the bulb appearing as a tube having one end closed, this represents a step in the early stages of development. From this stage to the completed bulb various methods of forming the reduced portion and cup portion may be employed but I have found it preferable to first form a flange 11 near the open end of the bulb and then the reduced portion 12. The flange 11 forms an annular collar whereby the bulb may be securely held in a fitting suitably threaded into the water jacket of a water cooled engine as shown in my cO-pending application filed March 1, 1928," Serial NO.

258,290. The portion of the bulb 10 which projects within the water jacket extends be low the flange 11 (Fig. 1) and this becomes in effect a closedchamber when the capillary is inserted withinthe bulb as hereinafter more fully described. i

- The groove or neck portion is then formed by suitable grooving wheels to the desired diameter. This completes the process of forming the bulb and the result is a one piece bulb formed in a way to be free from solder 0r leaky joints. 7

Obviously any other sequence of operationsmay be followedas for examplethe neck portion 13 may be formed before reducing the cup portion 12 to the desired size as shown in Fig. 4.

' The capillary tube 14: is inserted into the opening 15 formed by the neck portion 13 and soldered at 16. Thus it will be seen that only a very small amount of solder is required to securely hold the tube 14 in'place since the inner walls of neck 13 assist in rigidl ly holding the tube in place.

In order to protect the capillary tube 14 against short bends and other fractures I preferably employ a coiled spring 17. of slightlylarger' diameter than the capillary tube in order that any relative longitudinal movement between the tube 14 and coil 17 may easily take place. One end of the coil 17 is securely fastened within the cup shaped opening 12 of the bulb lO by crimping the portion'f12 into close contact with the coil.

Any other method of holding the coil within the socket 12 maybe employed asfor example, shallow screw threads may be formed on theinner surface of the cup and the coil may be screwed into place. However for convenience in manufacture and to save e21 pense the coil is held within the cup in the manner previouslyjdescribed. I

The other end of thecoil is left unfastened to permit relative movement between the coil and the tube'when it is bent or curved in any position desired,and as illustrated in Figure ts: tures that, from the standpoint of the prior art, fairly constitute essential characteristics 'ofeither the generic or specific aspects of this invention and, therefore, such 'adapta v tions should be, and are intended to be, com

" prehended within the meaning and range of equivalency of the following claims.

"H v ng u re ealed t inv ti n, claim as new and desire to secure the followingcornbinations and elements, or equivalents thereof, by Letters Patent of United States z--- j 1. As an article of manufacture a thermometer bulb comprising a metallic body portion having a socket shaped opening at one end, a reduced portion between said socket portion and body portion, a capillary one end formed with a reduced neck portion, with enlarged portions above and below said neck portion; there being an opening through said neck portion, acapillary tube extending through said opening and sup ported by the Walls thereof and being soldered thereto, the solder being placed in the pocketformed by the inner wall of thexouter enlarged portion and saidcapillary.

.3. A device of the character described comprising i a metallic thermometer bulb grooved at one. end to form a reduced neck portion and a socket portion, a capillary extending through said neck portion and isoldered thereto, a coiled spring surrounding it said capillary to protect the same against crushing or being kinked and means to hold said spring within said ,sooket'portion.

4. A device of the character described comprising an open ended thermometer bulb: grooved at said end to form a ferrule projecting from said groove, a capillary tubeinserted within Said bulb and fittingv withinthe grooved portion and extending through said ferrule, a guard for said tube, said guard being securely held within said fer rule by crimping the latter against the former, 1

5. As an articleof manufacture a ther mometer bulb comprising a one piece metallic structure having a bulb portion closedat its: lower end, an intermediate neck portion of a size to contain and support acapillary tube, a cup-shaped part adj acent the neck portion,

and an armored guard member supported in said cup-shaped part. V 6. In an instrument of the character specified the combination of a: capillary tube with a unitary metallic bulb Structure comprising the lower bulb=- portion, an intermediate neck portion and an upper enlarged portion, the capillary tube being inserted through said neck portion, the latter having its inner surface inclinedaway from the.

capillary tube to form a pocket for solder whereby the tube will be securely held.

7 In an instrument-of the character specifiedthe combination of a capillary tube with a'metallic bulb structure having a re-..

my name.

MOSES E. CHENEY. 

